Visualising Magnetic Fields: A 3d Dynamic Field Simulation

50.017 Graphics and Visualisation

Contributors: Seah Ying Xiang, Paul Ong, Loy Pek Yong

This OpenGL-based application visualizes magnetic fields in real-time from user-manipulated dipoles in a 3D environment. Built with GLFW, GLM, ImGui, and custom shaders, it offers real-time interaction, field line tracing, and other nifty features.

You can download and run it yourself here: [Latest Release, Windows Only]

Setup and Build Instructions (Windows with Visual Studio)

Prerequisites

• Visual Studio: Install Visual Studio 2019 or later (Community, Professional, or Enterprise) with the Desktop development with C++ workload from visualstudio.microsoft.com.
• GLFW: Download 32-bit Windows binaries from glfw.org/download.html. Copy glfw3.lib (e.g., from lib-vc2019) to the project’s libs folder.
• Dependencies: Ensure GLM, ImGui, and GLAD are in the includes folder. Shader files (shader.frag, field_line.vert, field_line.frag) should be in the project directory or a shaders subdirectory.
• Directory Structure:

MagneticFieldVisualizer/
├── includes/         # GLM, ImGui, GLAD
├── libs/             # glfw3.lib
├── src/              # main.cpp, camera.cpp, etc.
├── MagneticFieldVisualizer.sln
├── README.md

Visual Studio Setup

1. Open MagneticFieldVisualizer.sln in Visual Studio.
2. In Project Properties:
   • C/C++ > General: Add $(SolutionDir)includes to Additional Include Directories.
   • Linker > General: Add $(SolutionDir)libs to Additional Library Directories.
   • Linker > Input: Add glfw3.lib;opengl32.lib to Additional Dependencies.
   • Apply for Debug and Release configurations.
3. Verify source files (main.cpp, camera.cpp, etc.) are in Source Files and shaders are accessible.

Build and Run

1. Set configuration to Debug or Release and platform to Win64 (x64).
2. Click Build > Build Solution (Ctrl+Shift+B).
3. Run via Debug > Start Without Debugging (Ctrl+F5).
4. If errors occur:
   • Ensure glfw3.lib is in libs.
   • Check shader file paths in main.cpp.
   • Copy glfw3.dll to the executable directory if needed.

Key Features

• Dipole Interaction: Add, move (Ctrl+drag), or rotate (Alt+drag) dipoles, visualized as spheres with directional arrows.
• Field Visualization: Real-time field plane with color gradients (blue to red) for field strength, adjustable via ImGui.
• Field Line Tracing: Traces field lines using a 4th-order Runge-Kutta method with adaptive steps, parallelized for performance.
• Camera Controls: Perspective/orthographic modes, zoom (scroll), rotate (drag), and reset. No more snapping, we promise!
• ImGui Interface: Controls camera, dipoles, field lines, and visualization settings, plus FPS display.

UI Reference

Instructions Panel

This section displays key interaction controls to the user:

• Drag Anywhere – Rotate the scene
• Scroll – Zoom in/out
• CTRL + Drag – Move objects or pan the camera
• ALT + Drag – Rotate selected objects
• ESC – Exit the application

Camera Settings

Users can control the camera behavior and reset it when needed:

• Frames Per Second (FPS) is shown for performance feedback.
• Field of View (FOV) can be adjusted via a slider.
• Perspective Mode Toggle allows switching between perspective and orthographic views.
• Reset Camera Button returns the camera to its default position, rotation, and view target.

Field Plane Settings

This section configures the visualization of the plane used for field line rendering:

• Z Position Slider adjusts the depth placement of the field plane.
• Opacity Slider controls plane transparency.
• Sensitivity Slider modifies how strongly field strength variations appear visually.

Field Line Settings

Users can customize how magnetic field lines are rendered:

• Render Field Lines – Toggle field line visibility.
• Use Colored Field Lines – Enable color-coding based on field strength.
• Adaptive Step Size Toggle – Enables variable step lengths when tracing field lines.

Trace Settings:

• Step Size – Base step increment for tracing lines.
• Max Steps – Limits how long lines can grow.
• Adaptive Step Range – Minimum and maximum values for adaptive steps.
• Reference Field Strength – Used to normalize adaptive stepping.
• Apply Trace Settings – Applies the current settings to the tracer.
• Retrace Field Lines – Recomputes all field lines based on updated parameters.

Simulation Settings

This panel manages the dynamic simulation of magnetic dipoles:

• Simulation Speed Slider – Controls the time step scale.
• Start/Stop Simulation Button – Begins or pauses the simulation.
• Reverse Time Toggle – Reverses the direction of simulation time.
• Step Forward Button – Manually progresses the simulation by one frame.

Object Management Panel

Users can add, remove, and edit magnetic dipoles:

• Add Dipole Button – Adds a new magnetic dipole at the origin with default orientation.
• Randomize Dipoles Button – Randomly repositions and reorients all dipoles within a bounding volume.

Label Toggles:

• Show Labels – Display all dipole names.
• Show Labels on Hover – Only show labels when hovered.

Per-Dipole Controls

For each dipole in the scene:

• Dipole Header – Identifies the dipole by index (e.g., Dipole 1, Dipole 2...).
• Position Editor – Adjusts the dipole's 3D world position.
• Rotation Editor – Allows orientation input via Euler angles (in degrees).
• Moment Editor – Changes the magnetic moment magnitude.
• Remove Button – Deletes the dipole, reordering and updating all relevant lists and buffers.

Credits

• Field Line Tracing Algorithm: Adapted from Chen, Jun’s 4th-order Runge-Kutta method in “Numerical solution of tracing magnetic field line” (2020), el2718@mail.ustc.edu.cn.
• Dependencies: GLFW, GLM, ImGui, GLAD. Thanks for carrying our code’s weight.
• Team: We stumbled through quaternions and shaders so you can enjoy pretty magnetic fields.

Screenshots

License

Provided for educational use. Respect the licenses of GLFW, GLM, ImGui, and GLAD.